Motion skip is a coding tool that decodes a current macroblock by reusing some of the macroblock information from its neighboring reference views. Such macroblock information that may be used includes, for example, mode, motion vectors, reference picture indexes, and reference picture lists. Since motion related information is skipped for the current macroblock, some coding gains are achieved based on the fact that pictures in the neighboring views are likely to show consistent temporal motion.
Multi-view video coding (MVC) allows multiple inter-view reference pictures. However, with respect to multi-view video coding, it is not specified how motion skip mode is to be implemented such as, for example, which view and which block to select to extract the motion information.
Motion skip mode for multi-view video coding was proposed in a first prior art approach. In order to exploit the motion similarity between the neighboring views, the motion information is inferred from the corresponding macroblock in the neighboring view picture corresponding to the same temporal instance. The disparity vectors are specified in order to locate the corresponding macroblock in the neighboring view. Later, this proposed mode was simplified in a second prior art approach. Still another mode proposed in a third prior art approach improves the coding efficiency by adaptively selecting a picture between list 0 and list 1 to obtain the corresponding macroblock. In this mode proposed in the third prior art approach, an additional syntax element is introduced to signal which list should be used to obtain corresponding macroblock.
With respect to the first prior art approach it should be noted that the motion information is always obtained from the immediately neighboring views. Even when multiple inter-view reference pictures are used, views other than the immediately neighboring view are not selected to provide the motion information. This can limit the capability of the performance of motion skip mode. For example, if the corresponding macroblocks in the immediately neighboring views are coded in Intra mode, no motion information is able to be derived from the immediately neighboring views.